Capacitors are electronic devices including two terminals separated by insulating material. When there is a voltage difference between the two terminals, an electric field is created between the two terminals thereby storing electrical energy. The amount of electrical charge that can be stored on a capacitor per volt across the terminals is referred to as capacitance. Terminals are typically in the form of plates of various shapes, surface contours and sizes. The capacitance is generally a function of the dielectric constant κ of the dielectric layer, directly proportional to the area of the opposed terminals and inversely proportional to the distance between the terminals. Placing two or more capacitors in parallel results in a total capacitance of the combination that is equal to the sum of the capacitances of the individual capacitors. Placing two or more capacitors in series results in a total capacitance of the combination that is less than the capacitance of any of the individual capacitors. Series connected capacitors are commonly used in high-voltage situations because the high-voltage is divided among the capacitors. While providing capacitors of various sizes is usually not a problem outside of an integrated circuit, conventional integrated circuits are limited to relatively small capacitors because of size limitations. See, for example, U.S. Pat. No. 5,497,016.
A stack of capacitors connected in parallel has a low area footprint from the bottom capacitor in the stack of capacitors, and yet a large capacitance from the summed capacitance of the capacitors in the stack connected in parallel. However, the stacked capacitor is fabricated by many steps which results in increased complexity and cost of the overall integrated circuit. It would be desirable to take advantage of the low area footprint, large capacitance of the stacked capacitor, while minimizing additional fabrication complexity and cost resulting from the addition of the stacked capacitor to an integrated circuit.